Handling packages with SSE extensions

[Roland McGrath]

I don't think the suggestion of install-time hardware selection is wise.
We pretty much only have install-time hardware detection for the kernel and
X.  People know about those cases.  Those aside, people certainly do things
like replace a processor or move an installed disk to a different box.
When it's not really, really difficult to accomplish, I think the
selections should be done at startup time.  Someone mentioned an example
that does its own runtime selection, which is ideal but complicated.
The other approach is the one libc uses, which is hwcap-based DSO selection.